<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    ul li{
        list-style: none;
        width: 200px;
        height: 100px;
        text-align: center;
        line-height: 100px;
    }
    .item1{
        background-color: aliceblue;
    }
    .item2{
        background-color: blue;
    }
    .item3{
        background-color: brown;
    }
    ul{
        display: flex;
        margin: 0;
        padding: 0;
        width: 800px;
        height: 100px;
    }
    li{
        /* flex-grow: 0;
        flex-shrink: 0;
        flex-basis: 100px; */
        /* flex: 2; */
        /* flex: 1 0 100px; */
        /* align-self: flex-end; */
    }
    /* .item2{
        order:0 ;
        flex: 2;
    } */
     .item4{
        background-color: black;
        width: 50px;
        height: 50px;
        align-self: flex-end;
     }
</style>
<body>
    <ul>
        <li class="item1">1</li>
        <li class="item2">2</li>
        <li class="item3">3</li>
        <li class="item4"></li>
    </ul>
</body>
</html>